Inorganic particulates are used in various fields because they are excellent in strength, and heat resistance. Especially, silica particulates are used widely for antiblocking agents and lubricating agents for various kinds of films such as a polyester film, a polyimide film, and a fluororesin film; spacers such as an in-plane spacer for liquid crystal display elements, a spacer at a seal part for liquid crystal display elements, a spacer for EL display elements, a spacer for touch panels, and a gap-retaining material for various types of substrates such as ceramics, plastics, and the like; encapsulant for various electronic components such as a semiconductor encapsulant, a sealing material for liquid crystal, and an encapsulant for LED light emitting elements; light diffusion agents for light diffusion films, light diffusion plates, light-guiding plates, antiglare films, and the like; additives for cosmetics, such as white extender pigments; dental materials, etc.
In the case where silica particles are used for these applications, silica particles are known to be surface-treated with a surface treating agent such as a silane coupling agent in order to improve the surface characteristics or affinity with a resin as described in Patent Documents 1 to 3 for example.